On Wed, 2007-10-03 at 11:52 +0200, kirillkh wrote:
> 2007/10/3, skaller <[EMAIL PROTECTED]>:
> On Wed, 2007-10-03 at 10:37 +0200, kirillkh wrote:
> > That's interesting. Why didn't you use the version with the
> second
> > exception? The whole point is that it allows to avoid
> variant
> > allocations on the common code path. Do you have the same
> problem with
> > polymorphism in exceptions in Felix?
>
> There's no problem of any kind with exceptions in Felix...
> Felix has no dynamic exception handling at all.
>
> What do you do with division-by-zero or out-of-memory errors, then?
I think division by zero creates + or - inf for floats.
For integers, it does whatever the underlying compiler
does, probably abort the program in C++.
Out of memory depends on how you obtain the memory.
If you use the system allocator, it aborts the program.
If you call malloc() directly, you get a NULL pointer
as usual.
> [It does have 'non-local goto', which is a delimited
> continuation]
>
> Can you show the same code with a delimited continuation in Felix?
> (analogous to oleg's take of it)
What do you mean 'the same code'? :)
Below is a tutorial example:
/////////////////////////////////////
var x = 1;
proc run()
{
proc check()
{
if(x!=1) goto bad_x;
}
check();
print "good x"; endl;
x = 2;
check();
print "good x"; endl;
goto finished;
bad_x:>
print "bad_x"; endl;
finished:>
print "finished"; endl;
}
run();
//////////////////////////////////////
You can pass 'check' to any procedure and call it.
The point is, there is no way to fail to 'catch'
the 'exception'.
> Umm, well, unfortunately, I'm not entirely clear on the whole
> delimitation thing
Neither am I :)
> (read: I have no idea what it is, despite attempts to read oleg's
> papers). But I agree that undeclared exceptions that just get thrown
> out of nowhere are frequently not most pleasant (though they do save a
> lot of typing in some cases). My attempt to use an exception for
> fold_file wasn't constrained by having general-purpose exception
> polymorphism. The way oleg restated it in the list is just great if it
> works - especially since it avoids global declaration of the exception
> that is only used inside a single func.
I will read it .. haven't got to it yet.
--
John Skaller <skaller at users dot sf dot net>
Felix, successor to C++: http://felix.sf.net
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